Copper with highly preferred orientation has many excellent properties. Because copper crystal particles have highly preferred orientation, their properties are different in different orientations. For a microscopic point of view, different crystal orientations lead different atomic arrangements and densities, resulting in different thermodynamic and electromagnetic properties. In addition, from the chemical reactivity point of view, different crystal orientations lead to different reaction rate. For example, etching rates in different orientations of the crystal particles can be different. This is extremely beneficial for differential etching. There is no need to protect the copper surface (e.g., dry film protection, tin protection) for selective etching. At the same time, “side erosion” and “pool” effects can also be avoided.
Copper with highly preferred orientation, however, cannot be easily obtained, especially in the field of microelectronics. Currently, a relatively feasible method is electroplating, but this method requires pulse electrodeposition. The equipment requirements for pulse electrodeposition are extremely high. The current density for pulse electrodeposition is relatively low, usually less than 5 A/dm2, which results in low production efficiency. In addition, pulse electrodeposition cannot control the degree of preferred orientation to obtain copper crystal particles with preferred orientation.
There is a need for a convenient and efficient method for preparing copper crystal particles having a highly preferred orientation.